The much-lauded encryption app Signal has launched a beta program for a desktop version of the app, which will run through Google’s Chrome browser.

Signal Desktop is Chrome app that will sync messages transmitted between it and an Android device, wrote Moxie Marlinspike, a cryptography expert who had helped develop Signal, in a blog post on Wednesday.

The app comes from Open Whisper Systems, which developed Signal’s predecessors, Redphone and TextSecure, which were two Android applications that encrypt calls and messages. Both have been consolidated into Signal.

Signal Desktop won’t be able to sync messages with iPhone just yet, although there are plans for iOS compatibility, Marlinspike wrote. It also won’t support voice initially.

Signal, which is free, has stood out in a crowded field of encrypted messaging applications, which are notoriously difficult to engineer, and has been endorsed by none other than former U.S. National Security Agency contractor Edward Snowden.

The mobile version of Signal for the iPhone and Android uses end-to-end encryption for voice calls, messaging and sending photos.

Open Whisper Systems itself can’t see the plain text of messages or get access to phone calls since it doesn’t store the encryption keys.

Signal is open source, which allows developers to closely inspect its code. There has been growing concern that software vendors may have been pressured into adding capabilities in their products that would assist government surveillance programs. In theory, having open-source code means such tampering could be identified.

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